M818 emergency air problem

[gpp111]

I purchased a ten ton trailer to use with my M818. Hooked up both the service and emergency air to the trailer, the service air works just fine, but not getting any air pressure out of the emergency side. When you activate the emergency air on the steering column you hear a swoosh sound so perhaps there is a blockage in the line. Any suggestions what to do or look for?

 

[ichudov]

I purchased a ten ton trailer to use with my M818. Hooked up both the service and emergency air to the trailer, the service air works just fine, but not getting any air pressure out of the emergency side. When you activate the emergency air on the steering column you hear a swoosh sound so perhaps there is a blockage in the line. Any suggestions what to do or look for?

Did you find the tractor protection valve and did you activate it to supply the trailer through the emergency line?

 

[73m819]

Did you find the tractor protection valve and did you activate it to supply the trailer through the emergency line?

There is NONE on a m818

 

[gpp111]

So I wont look for one.

 

[doghead]

The lever on the column is for service brakes.

Are both of the valves open?

 

[doghead]

Do you have your lines crossed?

 

[gpp111]

You are correct, the problem is with the service air and not the emergency........still waking up this morning....you pull the lever on the column and no air comes out of the left glad hand and with the valve opened

 

[doghead]

Look for mudwasp nest in the line.

 

[73m819]

I purchased a ten ton trailer to use with my M818. Hooked up both the service and emergency air to the trailer, the service air works just fine, but not getting any air pressure out of the emergency side. When you activate the emergency air on the steering column you hear a swoosh sound so perhaps there is a blockage in the line. Any suggestions what to do or look for?

The steering column trailer brake control does NOT activate the emergency air but works the the same as stepping on the brakes as far as the trailer is concerned, in another words, a hand control for the trailer service breaks only.

Are you sure you have the air line hooked up correctly

Are BOTH shut off valves open

look for a mud dobber nest either in the tractor air line or the trailer air line, will outside air fill the emg. tank on the trailer

I type SLOOOOOOOOOOOOW

 

[gpp111]

I think the next step, assuming there is a blockage in the line, is to keep the air on for a couple of minutes, and if this does not work by blowing out whatever is clogging the line, I noticed there is at least one place on the airline between the cab and the hitch, what looks like a cap on the air line, so I will determine if there is air pressure to that location.

 

[gpp111]

The emergency air works just fine, I moved the empty trailer about 40 miles with no issues, air pressure built up fine to release the trailer brakes, but was unable to use the service air, meaning, I could not activate the trailer brakes manually. The valves at the glad hands were set exactly the same way, so I assume they were set properly since I had air on one side.

 

[Castle Bravo]

Check and see if air comes out of the service glad hand near the pintle when you step on the brakes. Whatever the case, that should help you narrow your search a bit.

 

[quickfarms]

First check for a blockage them function test. Do not rely on the color, tag or location because things can get switched.

Have you tried releasing the parking brake? The trailer air tanks are charged through the emergency side, this side will give you a steady flow of air and is where you hook up the tire inflator. This side is called the emergency side because if the pressure drops to about 40 lbs the relay valve should automatically apply the brakes if everything is working. The service side only gives you a shot of air, to trigger the relay valve to apply the brakes, when you either press the foot valve or trolley valve.

Read the TM and the air brake portion of the CDL manual

 

[fasttruck]

Dose the same thing happen when you operate the foot brake as the hand applicator valve ? This would indicate if problem is in hand valve or whole service system. I assume brake on tractor works normally when foot brake is applied.

 

[reb87]

Pull steering column brake lever and go check the glad hand where air is not coming out. Try valve both ways, they are not always the same nor are they always marked properly..

 

[gpp111]

I believe I was doing everything correctly but will go through the entire sequence again to make sure there is not something I overlooked. Can't do this until Wednesday, and will let you know what I find out. I will try every possible combination.
appreciate the input.

 

[gpp111]

Rebel 87 you were right, the two valves work differently and I do have air at both glad hands. Appreciate everyone's assistance with this, now, non issue!